1. Technical Field
The present invention relates to a method for producing, and a method for driving, a liquid-jet head in which a part of a pressure generating chamber communicating with a nozzle orifice for jetting a liquid is constructed of a vibration plate, a piezoelectric element is formed on the surface of the vibration plate, and the liquid is jetted by the displacement of the piezoelectric element.
2. Related Art
Among liquid-jet apparatuses is, for example, an ink-jet recording apparatus having an ink-jet recording head comprising a plurality of pressure generating chambers for generating a pressure for ink droplet ejection by a piezoelectric element or a heat generating element, a common reservoir for supplying ink to each pressure generating chamber, and a nozzle orifice communicating with each pressure generating chamber. With this ink-jet recording apparatus, ejection energy is applied to ink in the pressure generating chamber communicating with the nozzle orifice corresponding to a print signal to eject an ink droplet through the nozzle orifice.
The ink-jet recording head, in which a part of the pressure generating chamber communicating with the nozzle orifice for ejecting an ink droplet is constructed of a vibration plate, and the vibration plate is deformed by the piezoelectric element to pressurize ink in the pressure generating chamber, thereby ejecting an ink droplet through the nozzle orifice, is put to practical use in two types: one of the types using a piezoelectric actuator in a longitudinal vibration mode expanding and contracting in the axial direction of the piezoelectric element, and the other type using a piezoelectric actuator in a flexural vibration mode.
A drive waveform comprising a rectangular wave has been used as a drive signal for driving the piezoelectric element of such an ink-jet recording head. This drive waveform comprising the rectangular wave has a step of discharging from an intermediate drive voltage in a wait state to expand the pressure chamber, thereby sucking ink into the pressure chamber; a step of maintaining a minimum drive voltage; a step of charging to contract the pressure generating chamber, thereby ejecting ink; a step of maintaining a charge final voltage; and a step of discharging to return to the intermediate drive voltage, and an ink droplet is discharged by this drive waveform (see, for example, JP-A-1998-250061).
A proposal has been made for a technology which makes it possible to carry out gradation recording by ejecting ink droplets of different weights through the same nozzle (see, for example, JP-A-1998-081012). With such a technology, a plurality of the same pulse signals are generated within one recording cycle to produce a plurality of fine ink droplets, and these plural fine ink droplets are integrated, before their landing on a recording paper, to produce a large ink droplet.
The pulse signals generated in plural numbers within one recording cycle are defined in conformity with the design of an ink-jet head. Generally, they have a waveform having a vibration damping step of damping the vibration of ink after the step of ejecting ink. A plurality of continuous pulse signals can produce an ink droplet of a predetermined size, on the one hand, while one pulse signal can produce, for example, a fine ink droplet, on the other hand.
According to the above-described techniques, however, if variations in the capacity of supplying ink occur owing to the manufacturing error of the ink-jet recording head, particularly, the manufacturing error of an ink supply port for supplying ink to the reservoir, predetermined sizes may fail to be maintained for large and small ink droplets.